Diacetylenic alcohol corrosion inhibitors

ABSTRACT

The corrosion of ferrous metals by corrosive acids at elevated temperatures is inhibited by adding to environments containing the acids an effective amount of a novel α, Ω (hereinafter &#34;alpha&#34;, &#34;omega&#34;, respectively) diacetylenic diol (e.g., with two acetylenic functionalities) having the structural formula: ##STR1## where R is an aliphatic, alicyclic or aromatic residue containing from 1 to about 12 carbon atoms and may include one or more functional groups such as halogen atoms, carbonyl, carboxyl, carbamyl, amino, formyl or nitroso radicals or other functional groups without impaired performance. The diacetylenic diols may be employed in combination with other corrosion inhibitors.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to corrosion inhibitor compositions useful forretarding the corrosion of ferrous metals by corrosive acids especiallyfor metals in an underground oil field location, and is particularlyconcerned with novel diacetylenic alcohols which are especiallyeffective corrosion inhibitors.

2. Description of the Prior Art

The use of acetylenic alcohols for inhibiting the corrosion of ferrousmetals has been proposed in the past. Although compounds such aspropargyl alcohol which contain one acetylenic linkage and one hydroxylgroup have been found effective, studies have shown that certainacetylenic diols perform very poorly. These materials have the followingstructures: ##STR2## It has been postulated that one reason for this maybe that the diols undergo an acid catalyzed cyclization to form adihydrofuran as indicated by Formula III below or undergo waterelimination to produce the conjugated ENE-YNE structure indicated byformula IV below. ##STR3##

It may also be that ethynyl hydrogen group, -- C .tbd. C -- H, and acarbinol group attached directly to the acetylenic linkage, ##STR4## areimportant if the acetylenic compound is to be an effective acidcorrosion inhibitor. Any compound employed for this purpose should notbe sterically hindered.

SUMMARY OF THE INVENTION

The present invention provides a novel class of acetylenic diolcompositions which are surprisingly effective as corrosion inhibitorsfor ferrous metals. The improved inhibitors of the invention have thegeneral formula: ##STR5## where R is an aliphatic, alicyclic or aromaticresidue containing from 1 to about 12 carbon atoms and may include oneor more functional groups such as halogen atoms, carbonyl, carboxyl,carbamyl, amino, formyl or nitroso radicals or other functional groupswithout impaired performance.

The preferred diacetylenic diols of the invention are those preparedfrom alkyl residues and have the following structural formula: ##STR6##where n is an integer from 1 to 12, preferably from 4 to 8. Examples ofsuch compounds include 3,5-dihydroxy-1,6 -heptadiyne,3,6-dihydroxy-1,7-octadiyne, 3,7-dihydroxy-1,8 -nonadiyne,3,8-dihydroxy-1,9-decadiyne, 3,10-dihydroxy- 1,11-dodecadiyne,3,12-dihydroxy-1,13-tetradecadiyne, 3,14-dihydroxy-1,15-hexadecadiyne,and the like. Such compounds have excellent corrosion inhibitingproperties and do not readily undergo dehydrocyclization and otherreactions which destroy their effectiveness.

These diacetylenic diols are used to inhibit the corrosion of ferrousmetals such as steel by hydrochloric acid, sulfuric acid, nitric acidand other corrosive acid solutions by adding them to the solutionscontaining these acids in effective concentrations. The materials of theinvention are particularly effective for combatting corrosion atelevated temperatures and below ground in an oil field environment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The alpha, omega diacetylenic diol compositions of the invention may beprepared in a number of different ways. Suitable starting materialsinclude, the alpha, omega dialdehydes such as succinic dialdehyde,malonic dialdehyde, adipaldehyde, sebacic aldehyde and the like. Theyalso may be made from alpha, omega dialdehyde precursors such as alpha,omega dinitriles, cyclic olefins such as cyclohexene and cycloheptene,and 1,2 cyclohexane diol.

The dialdehydes can be prepared by the partial reduction of thedinitriles, by the reductive ozonization of cyclic olefins as describedby F. G. Fisher and K. Lowcubert, Chem. Ber. 66, 666 (1933), or byoxidation of 1,2 cyclohexane diol or similar dihydroxy alicycliccompounds in the presence of lead acetate as described by Stanley R.Sandler and Wolf Karo, "Organic Functional Group Preparations," page149, Academic Press, New York, N.Y. (1968), and by J. English and E. W.Barber, General American Chemical Society, 71 3310 (1949). Certain ofthe dialdehydes are used as chemical intermediates in the manufacture ofnylon and related products and are available from commercial sources.The use of adipaldehyde and similar dialdehydes containing a total offrom about 6 to about 14 carbon atoms per molecule as starting materialsis generally preferred.

The dialdehydes which are employed as the preferred starting materialsfor the preparation of the diacetylenic alcohols can be converted intothe corresponding alcohols by a variety of different methods. Severalsuch methods are described by Thomas F. Rutledge in "AcetylenicCompounds," Reinhold Book Corporation, New York, N.Y. (1968). One suchmethod involves treatment of the dialdehyde with ethynyl magnesiumbromide in tetrahydrofuran as described by Lars Skatterbol, E. R. H.Jones and Mark C. Whiting in Org. Syn. Coll., Vol. IV, pp. 792-795(1963). Other methods which may be used for production of thediacetylenic alcohols will be familiar to those skilled in the art.

The diacetylenic alcohols which are prepared as described above have thegeneral formula ##STR7## where R is an aliphatic, alicyclic or aromaticresidue containing from 1 to about 12 carbon atoms and may include oneor more other functional groups such as halogen atoms, carbonyl,carboxyl, carbamyl, amino, formyl or nitroso radicals or otherfunctional groups without impaired performance.

The alpha, omega diacetylenic alcohols which have been prepared fromalkyl residues are preferred for purposes of the invention. These diolshave the following structural formula: ##STR8## wherein n is a smallnumber from 1 to 12, preferably from about 4 to 8. Compounds of thistype which are corrosion inhibitors in accordance with the inventioninclude 3,5-dihydroxy-1,6-hepadiyne, 2,6-dihydroxy-1,7-octadiyne,3,7-dihydroxy-1,8-nonadiyne, 3,8-dihydroxy-1,9-decadiyne,3,7-dihydroxy-5-methyl-1,8-nonadiyne, 3,8-dihydroxy-6-dimethyl-1,9-decadyne, 3,10-dihydroxy-5-methyl-7-ethyl-1,11-dodecadiyne, 3,12-dihydroxy-7,8-dimethyl-1,13 -tetradecadiyne,3,12-dihydroxy-1,13-tetradecadiyne, 3,14-dihydroxy-7,8,9-trimethyl-1,15-hexadecadiyne, 3,14-dihydroxy-1,15-hexadecadiyneand the like.

The alpha, omega diacetylenic alcohols are useful for inhibiting thecorrosion of iron, steel, stainless steel and other ferrous metals bynonoxidizing acids such as hydrochloric acid, sulfuric acid, phosphoricacid, acetic acid and the like. They are useful at atmospherictemperatures as well as at elevated temperatures up to about 200° F. andin some cases even higher. They are effective with both dilute andconcentrated acids, including commerical concentrated hydrochloric acidof 37% strength. Applications in which they are particularly usefulinclude oil well acidizing, metal pickling, cleaning and polishingbaths, boiler cleaning compositions and the like.

The novel diols of the invention are generally utilized by dissolving ordispersing them, alone or in combination with other materials, in theacid solution which is to be inhibited. Other standard inhibitorconstituents can be employed in conjunction with the diols such assurface active agents, wetting compounds, long chain aliphatic amines,alkaryl, polyethylene oxyethanol, quaternary derivatives of heterocyclicnitrogen compounds and halomethylated aromatic compounds,perfluoroalkylimidazolines and the like. The diols are normally employedin concentrations between about 0.005% and about 2.0%, preferably 0.05%to 1.0%, based on the volume of the aqueous acid solutions to which theyare added, and are particularly effective when used in concentrationsbetween about 0.1 and about 1.0% by volume.

The nature and objects of the invention are further illustrated by thefollowing examples.

EXAMPLE 1

Adipaldehyde was prepared by the oxidation of cyclohexane diol with leadacetate using the procedure described by Sandler and Karo in "OrganicFunctional Group Preparation," page 149, Academic Press, New York, N.Y.(1968). The adipaldehyde was then converted to3,8-dihydroxy-1,9-decadiyne by treatment with ethynyl magnesium bromidein tetrahydrofuran by first fitting a 1000 ml three-neck flask with astirrer, addition funnel, nitrogen tube and condenser.

Into this were placed 24 g. of magnesium turnings and 300 ml ofanhydrous tetrahydrofuran. A solution of 100 g. of ethylbromide inanhydrous tetrahydrofuran was then slowly added to the magnesiumturnings until the formation of ethyl magnesium bromide was complete.This step and the subsequent reaction steps were carried out under drynitrogen gas.

The ethyl magnesium-bromide solution was then transferred to a largepressure equalizing addition funnel by means of a bent glass tube andnitrogen pressure. 400 ml of tetrahydrofuran was then placed in a dryglass 200 ml reaction kettle equipped with a gas inlet tube, athermometer, a stirrer, and the pressure equalizing addition funnel.Acetylene was added to the gas dispersion tube with slow addition of theethyl magnesium bromide. This was continued until the formation ofethynyl magnesium bromide was complete.

The ethynyl magnesium bromide prepared as described above was cooled inan ice-methanol bath. A solution of 39.0 g. of adipaldehyde in 50 ml ofanhydrous tetrahydrofuran was added to the stirred ethynyl magnesiumbromide solution. After addition had been completed, the mixture wasallowed to warm to room temperature with stirring over a period of 10hours.

The reaction mixture was then added to a 4-liter separatory funnelcontaining 1.5 liters of saturated aqueous ammonium chloride solution.The resulting mixture was shaken and then allowed to separate into anorganic top phase and aqueous lower phase. The organic phase was removedand the lower phase was then extracted three times with ether to recoverany organic materials present.

Following this, the organic phase and ether solutions were combined,dried over magnesium sulfate, and filtered. The ether andtetrahydrofuran were removed from the filtrate by distillation. Vacuumdistillation of the product, which had a boiling point between 130° and141° C. at 9 mm of mercury, yielded a clear viscous liquid that slowlysolidified after several days. The yield was 39.2 g., 69% of thetheoretical yield of 3,8-dihydroxy-1,9-decadiyne. Analysis showed anempirical formula of C₁₀ H₁₄ O₂. Infrared spectrum analysis and protonmagnetic resonance spectrum analysis confirmed that the product obtainedwas 3,8-dihydroxy-1,9-decadiyne.

EXAMPLE 2

Corrosion tests were carried out using propargyl alcohol and3,8-dihydroxy-1,9-decadiyne prepared as described in Example 1 above.These tests were conducted by preparing 100 ml samples of 15%hydrochloric acid in separate sample bottles. Test coupons of steel cutfrom J-55 oil well tubing were placed in the sample bottles and 0.5% byvolume of the selected inhibitors were added to the bottles. The bottleswere then held at a temperature of 200° F. and at ambient pressure for aperiod of 4 hours. Following this, the samples were moved from the acidsolution, washed repeatedly to remove any remaining acid, and thendried. The dried samples were weighed to determine the weight loss andpermit calculation of the corrosion rate. The results obtained are shownin Table I below:

                  TABLE I                                                         ______________________________________                                        Corrosion Tests                                                                                              Corrosion                                                          Weight Loss,                                                                             Rate                                           Inhibitor           grams      lb/ft.sup.2                                    ______________________________________                                         ##STR9##            0.3050     0.0216                                         ##STR10##           0.0412      0.00292                                      ______________________________________                                    

It is noted from the above table that the corrosion rate with the3,8-dihydroxy-1,9-decadiyne was nearly an order of magnitude lower thanthat with the propargyl alcohol. This low corrosion rate under therelatively severe conditions of the test demonstrates that the alpha,omega diacetylenic alcohols are surprisingly more effective as corrosioninhibitors than propargyl alcohol and similar materials employed in thepast.

EXAMPLE 3

Following the work reported above, additional corrosion tests werecarried out with three different grades of steel used in oil well tubingand three acetylenic alcohols. One of the alcohols was3,8-dihydroxy-1,9-decadiyne prepared as described in Example 1 above andthe other two were acetylenic alcohols outside the scope of thisinvention. One of these was 2,5-dimethyl-3-yn3-2,5-diol and the otherwas 2,7-dimethyl-3,5-octadiyne-2,7 diol. Sample bottles containing 100ml of 15% hydrochloric acid and weighed steel corrosion coupons wereprepared as described in Example 2.

To each of these bottles were added one of the acetylenic alcohols in aconcentration of 0.25 or 0.5% by volume. The bottles were then held at200° F. and ambient pressure for a period of 4 hours. Following this,the samples were removed, washed and dried, and weighed to permitdetermination of the weight loss and corrosion rate. Results are shownin Table II.

                                      TABLE II                                    __________________________________________________________________________    Comparative Corrosion Tests                                                                       Inhibitor                                                                     Concentration,                                                                        Steel                                                                              Weight                                                                             Corrosion Rate,                         Inhibitor           Vol. %  Coupon                                                                             Loss, g.                                                                           lb/ft.sup.2                             __________________________________________________________________________    3,8-Dihydroxy-1,9-decadiyne                                                                       0.25    P 105                                                                               0.5916                                                                            0.0420                                  "                   0.25    N 80  0.6110                                                                            0.0434                                  "                   0.25    J 55  0.1437                                                                            0.0102                                  "                   0.50    P 105                                                                               0.0809                                                                            0.00574                                 "                   0.50    N 80  0.0432                                                                            0.00307                                 "                   0.50    J 55  0.0350                                                                            0.00248                                 2,5-Dimethyl-3-yne-2,5-diol                                                                       0.25    P 105                                                                              12.2687                                                                            0.942                                   "                   0.25    N 80 13.3726                                                                            0.950                                   "                   0.25    J 55 10.2762                                                                            0.730                                   "                   0.50    P 105                                                                              13.3492                                                                            0.948                                   "                   0.50    N 80 13.3404                                                                            0.947                                   "                   0.50    J 55 11.8972                                                                            0.845                                   2,7-Dimethyl-3,5-octadiyne-2,7-diol                                                               0.25    P 105                                                                              13.1646                                                                            0.935                                   "                   0.25    N 80 11.8172                                                                            0.839                                   "                   0.25    J 55 12.3035                                                                            0.874                                   "                   0.50    P 105                                                                              12.9889                                                                            0.922                                   "                   0.50    J 55 10.8834                                                                            0.708                                   __________________________________________________________________________

Again, it can be seen that the alpha, omega diacetylenic alcohols of theinvention are surprisingly more effective than closely relatedacetylenic alcohols which lack the structure of the materials of theinvention.

What is claimed is:
 1. A relatively non-corrosion composition of mattercomprising water and a quantity of nonoxidizing acid sufficient to forman aqueous acid ordinarily corrosive to ferrous metals, wherein thecorrosive tendency of said aqueous acid to ferrous metals issubstantially diminished by the presence of about 0.005 to 2.0 vol. % ofan α, Ω-diacetylenic diol having the structural formula: ##STR11## whereR is an aliphatic, alicyclic or aromatic residue containing from 1 to 12carbon atoms.
 2. The composition according to claim 1 wherein saiddiacetylenic diol is 3,8-dihydroxy-1,9-decadiyne.
 3. The composition ofclaim 1 wherein said diacetylenic diol has the structural formula:##STR12## wherein n is an integer ranging from 1 to
 12. 4. Thecomposition of claim 3 wherein said n is an integer ranging from 4 to 8.5. A process for inhibiting the corrosion of ferrous metals in contactwith aqueous nonoxidizing acid, said process consisting essentially ofmaintaining in said acid an effective amount of between about 0.005 toabout 2.0 vol. % of an α, Ω-diacetylenic diol having the structuralformula: ##STR13## where R is an aliphatic, alicyclic or aromaticresidue containing from 1 to 12 carbon atoms.
 6. A process according toclaim 5 wherein said diol is 3,8-dihydroxy-1,9-decadiyne.